The present invention relates generally to the packaging of electrical components, and more particularly, to a method of packaging an imaging sensing circuit.
There has been a constant demand for smaller and smarter industrial and consumer electronic products such as digital cameras, camcorders, audio players, etc. Such miniaturization and increased functionality has benefited from advances in the design and manufacturing of semiconductor circuits and wafers. There has also been a marked increase in the use of optical and image sensors in electronic products. At present, all of the available optical and image sensors are packaged in conventional, rigid base carriers such as ceramics or organic substrates. Rigid organic substrates are generally made from BT (bismaleimide-triazine) resin, ceramics, or FR-4.
For example, U.S. Pat. No. 6,268,231 discloses a CCD package having a plastic base structure, a flexible plastic circuit board mounted on the base structure, a plastic rim mounted on the circuit board, a CCD sensor mounted on the circuit board and inside the rim, and a glass cover mounted on the rim. The CCD sensor is wire bonded to the circuit board. The plastic base structure, circuit board and rim, not to mention the glass cover, make for a relatively thick package. U.S. Pat. Nos. 6,034,429, 6,268,654 and 6,143,588 also disclose a CCD package including an IC die mounted on and wire bonded to a first side of a BT substrate, a bead or dam formed in varying manners around the IC die, a glass lid attached to the bead, and solder balls attached to a second side of the BT substrate. All of these packages are relatively thick. Thus, although the package size of image sensors has decreased, there is still room for improvement, as lower cost and smaller package footprint and height are critical in assuring that more intelligence and functionality are incorporated into new electronic devices.